The present invention relates to a scroll-type fluid machine having a fixed scroll member and a movable scroll member.
Various scroll-type fluid machines are generally known and widely used in an air conditioning system of an automobile and others. Referring to FIG. 1, description will presently be made as regards a scroll-type fluid machine in an earlier technology.
The scroll-type fluid machine is for use in the air conditioning system of the automobile and has a font housing 1 and a rear housing 2 which is coupled with the front housing 1. The rear housing 2 includes therein a movable scroll member 3 and a fixed scroll member 4. The movable scroll member 3 has an end plate 3a and an involute member 3b which is integrally formed on one surface of the end plate 3a. Similarly, the fixed scroll member 4 has an end plate 4a and an involute member 4b integrally formed on one surface of the end plate 4a. The fixed scroll member 4 is fixed at its end plate 4a to the rear housing 2. On the other hand, the movable scroll member 3 is received at the end plate 3a by the front housing 1 through a ball coupling 5, and the involute member 3b of the movable scroll member 3 is engaged with the involute scroll member 4b of the fixed scroll member 4, with a compression space 6 for a refrigerant gas formed between the two involute members 3b and 4b. The ball coupling 5 has a mechanism which prevents a rotation of the movable scroll member but permits an orbital motion of the movable scroll member along its orbital way. A detailed description of the mechanism and operation of the ball coupling will be made presently in the instant application.
A main shaft 7 is provided in the front housing 1 such that its one end is exposed outside the front housing 1. The main shaft 7 is rotatably supported in the front housing 1 by means of radial bearings 8, 9. On the outer circumferential surface of the front housing 1 is mounted a rotor 12 which is rotatably supported by a radial bearing 11. The rotor 12 is connected with an automobile engine through a belt means (not shown). An armature 13 is provided to an end surface of the rotor 12 with a spaced confronting relation with a very small space relative to the end surface of the rotor 12, and the armature 13 is axially movably supported by an end of the main shaft 7 so that the armature 13 can be displaced resiliently in the axial direction. Further, an electromagnetic solenoid 14 is supported in the front housing 1. The rotor 12, the armature 13 and the electromagnetic solenoid 14 form in combination an electromagnetic clutch device. In other words, when an electric current is applied to the electromagnetic solenoid 14, the armature 13 is attracted and adhered to the end surface of the rotor 12 into a combined form and a driving force of the automobile engine is transmitted to the main shaft 7 through the rotor 12 and the armature 13 so that the main shaft 7 is rotated when the engine is driven.
An eccentric pin 15 is disposed to the other end of the main shaft 7. On the opposite surface of the end plate 3a of the movable scroll member 3, an eccentric bush 16 is rotatably supported by a radial bearing 17, and the eccentric pin 15 is inserted into an eccentric hole 16a of the eccentric bush 16.
When the main shaft 7 is rotated, the eccentric pin 15 is rotated around an axis of the main shaft 7 and the movable scroll member 3 is driven in an orbital motion through the eccentric bush 16. This forces the compression space 6 to move toward a central portion along the involute members 3b, 4b, as the compression space 6 reduces its volume to thereby proceed a compression operation of the refrigerant gas. The compressed refrigerant gas passes through a discharge hole 18 which is provided, in correspondence with the central portion of the machine, on the end plate 4a of the fixed scroll member 4 to open a discharge valve 19 and is then discharged into a discharge chamber 21 which is formed between the end plate 4a and the rear housing 2. In FIG. 1 of the drawing, reference numeral 22 represents a valve holder which serves to press and hold the discharge valve 19.
The refrigerant gas of the discharge chamber 21 is then discharged outside the machine through a discharge port (not shown). On the other hand, the refrigerant gas which is sucked into the suction chamber 23 from a suction port (not shown) of the rear housing 2 is received in and held by the compression space 6 at the outer circumferential portion of the involute members 3b and 4b.
The ball coupling 5 includes a fixed side race 24 fixedly supported by the front housing 1, a movable side race 25 fixedly supported by the end place 3a of the movable scroll member 3, and a plurality of balls 26 disposed between the fixed side race 24 and the movable side race 25. Each of the fixed side and movable side races 24 and 25 is made of a ring-like plate having a plurality of annular grooves for rotation of the balls 26 such that each ball 26 corresponds with each annular groove.
In order to control an axial clearance between the fixed scroll member 4 and the movable scroll member 3, the front housing 1 is in an axially confronting relation with the rear housing 2 with one or more spacers or shims 27 and fixedly coupled with each other by bolts 28. A axial dimension of the shim 27 is suitably selected in accordance with an axial clearance between the fixed scroll member 4 and the movable scroll member 3.
However, it is difficult to select the axial dimension of the shim 27 in an assembly of the scroll-type fluid machine described above, because various kinds of shims must be prepared and a suitable one or more of them must be initially selected and then adapted repeatedly by trial and error to find the most suitable one(s)to finally decide the number and thickness of the shims. Further, there is a problem of supervising a number of, and various kinds of, shims.